I’ve already mentioned before some of the things I do know about police training, and they are specifically trained not to put a knee on somebody at all as part of a hold once on the ground. A knee in the back from standing to get them on the ground, but no where else, and at no other time, because of the dangers posed. And often even a knee against the back is supposed to be thoroughly justified afterwards.
For decades, long before even chokeholds were being questioned, police academies and departments specifically trained officers to never use a knee on the neck, because there is actually no way whatsoever to make it safe. No amount of practice, no skill. It is always dangerous. It will always lead to highly limited breathing, as well as damage to the muscles and tendons.
Only soldiers and highly militarized police use this method, and even most soldiers are taught to limit the length it is used if they’re trying to capture someone, because of the risk of serve injury and death. The only time a soldier would stay on someone’s neck for 9 minutes and 29 seconds (even for 1 minute), is to specifically to hold down the enemy while killing them. As far as militarized police … well, in the places that actually have them, it has been found that policing mostly consists of beatings and murders.
Seriously, even Spanish police, with a long known habit of shooting quickly with automatic weapons, still aren’t really militarized, and they aren’t shooting nearly as much as a lot of people claim, and never really have. And when you stop and talk with them, even if they are about to arrest you, they were genuinely respectful as long as you don’t get violent and abusive.
The one example of Spanish police I know of shooting someone running away (with and SMG, no less) was in the 1980s, a man was drunk, loud, and busting up cars as he was walking down the street. The police saw him, told him to stop, and he ran. One fired a burst, took him down, and then they got him in an ambulance. He would soon after have been court martialed and dishonorably discharged from the US Navy, but I don’t know that part, because he sure never got back on my dad’s ship. (Extra trivia note, before going on shore leave, the ship’s XO had told everyone that the police in Spain are armed with fully automatic weapons, but it’s okay, they just use rubber bullets. The first they do, or did then, the second they clearly do not.)